U.S. Pat. No. 4,085,403, Meier et al, discloses a remote control system in which, selectively, receivers are controlled under command from a central station. To effect the control, the central station has a counter which counts in synchronism with clock pulses transmitted by the central station over a ring bus system. The receivers also have counters which count in the same synchronism, under control of the clock pulses. Specific receivers are enabled are remotely controlled by providing an additional control bus in the ring bus system which provides a pulse synchronously with a specific count state of the transmitter and, hence, also of the specific receiver. Upon coincidence of the count state of the counter associated with the specific receiver, and the count state of the transmitter counter, a coincidence gate is enabled which then provides a control signal to connect the respective load, associated with the receiver. The system is explained in detail in the aforementioned patent, the disclosure of which is incorporated by reference.
To program a receiver, as described in the aforementioned patent, it is necessary to provide suitably programmed logic interrogation gates connected to the receiver counter. The interrogation gates must be so arranged that they respond only when a certain count state is reached by the counter. The counter itself recycles, in sequences which are termed "selection cycles". When, within a selection cycle, an output signal appears at the respective interrogation gate, a suitable coincidence gate then is enabled to permit connection of the load.
To program specific loads, it is necessary to connect specifically programmed interrogation stages with the counter, each interrogation stage being associated with a predetermined load. This places substantial skill requirements on personnel installing, maintaining or replacing elements used in the overall system.